In the treatment of thalassemia, iron poisoning from frequent transfusions is the primary cause of death. If neocytes only are transfused then the frequency of transfusions is cut by half. To collect neocytes, a method was needed to continuously monitor the hemoglobin concentration of the output of an IBM continuous flow cell separator. A device was designed and built that continuously measures hemoglobin concentration non-invasively. The sensor head fits over the output tube and uses optical methods to measure the hemoglobin concentration. The device will measure from 0-12g% concentration with less than .3g% error.